Dasyrhicnoessa dolichopoda, Munari, Lorenzo, 2014

Munari, Lorenzo, 2014, New Indo-Pacific species of Dasyrhicnoessa Hendel, 1934 and Pseudorhicnoessa Malloch, 1914 (Diptera: Canacidae: Tethininae), Zootaxa 3784 (3), pp. 281-293 : 282-283

Dasyrhicnoessa dolichopoda sp. nov.

( Figs 1–2 )

Diagnosis. This species is distinguished from congeners mainly by the following combination of characters: body length 2.28 mm, wing length 1.78 mm; 2 pairs of inclinate interfrontal setae, with no additional setulae between them; antenna unusually large and porrect, with basal flagellomere entirely black; vertical diameter of eye about 7.2 times as long as genal height; 4 peristomal setae, including true vibrissa; acrostichal setulae arranged in 4 irregular rows; 1 long supra-alar seta and 1 shorter seta arising just a little ventrally; legs slender, perceptibly longer than usual; foretibia and foretarsus entirely black; forefemur slightly swollen, hind femur simple, not swollen; anteroventral ctenidial comb of forefemur not discernible (due to collapse and twisting of femur); posteroventral armature of male mid femur with a long row of spine-like setae; hind femur without long setae; male terminalia with anterior surstylus rod-like, distinctly swollen apically, protruding forward, bearing some thin setulae on ventral side; posterior surstylus short, stumpy, with several stout spinulae and very robust setulae on ventral side.

Description. Size. Body length 2.28 mm, wing length 1.78 mm.

Habitus. Small fly, with yellowish brown body and yellow legs, excepting black foretibia and foretarsus; setal vestiture black; wing pale grey.

Head. Distinctly higher than long; vertex and occiput grey, frons yellow, both sides of ocellar triangle with a large golden patch, fronto-orbital plate narrow, white, face widely membranous, diaphanous, remarkably depressed, gena narrow, yellowish grey; postocellar setae weak, inclinate as well as slightly proclinate; medial vertical seta slightly longer than lateral vertical seta; postocular setae arranged in 1 irregular row, dorsal postocular seta moderately strong, inclinate; ocellar triangle grey microtomentose, bearing a few minute setulae in addition to usual long ocellars; 3 strong, lateroclinate fronto-orbital setae intermixed with scattered, minute setulae; 2 pairs of inclinate interfrontal setae, anterior setae weak and thin, posterior pair with longer, stronger setae, no additional setulae between interfrontal setae; antenna unusually large and porrect, with scape and pedicel yellow, basal flagellomere entirely black; arista brown, with micropubescence formed by moderately long hairs; eye very large, vertically oblong, densely micropubescent, bearing a multitude of interfacetal ommatrichia, its vertical diameter about 7.2 times as long as genal height; 4 peristomal setae, including true vibrissa, posterior seta smaller and weaker; clypeus narrow; mouthparts yellow, with labellum about as long as or slightly shorter than buccal cavity length.

Thorax. Yellowish brown, with a median, broad, longitudinal black stripe on scutum; 1+3 dorsocentral setae; acrostichal setulae arranged in 4 irregular rows; acrostichal prescutellar setae long; 3 postpronotal setae intermixed with a few tiny setulae, each major seta with a different orientation; 1 presutural; 2 notopleurals; 1 long supra-alar seta and 1 shorter seta arising just a little ventrally; 2 postalars; a few irregular rows of scattered setulae between dorsocentrals and the lateral side of scutum; scutellum with 2 pairs of setae; 1 proepisternal; 1 proepimeral; anepisternum sparsely setulose, with 3 postero-marginal setae and 1 dorsally oriented, posterodorsal seta; katepisternum sparsely setulose, with 1 seta on posterodorsal margin; anepimeron and meron without setae and setulae. Legs. Mostly yellow, excepting black foretibia and foretarsus; apical 2 – 3 tarsomeres of mid and hind legs partly to fully brown infuscate; forecoxa with 2 long setae in addition to some weaker and shorter setae, mid and hind coxae each with a long seta; forefemur slightly swollen, hind femur simple, not swollen; forefemur with a few posterodorsal and posteroventral long setae; if present, the anteroventral ctenidial comb of forefemur is not discernible, due to collapse and twisting of femur; foretibia and foretarsus black, evenly short-setulose; posteroventral armature of male mid femur with a long row of spine-like setae; mid tibia and tarsus evenly setulose, except for an apicoventral spur on mid tibia; entire hind leg evenly short-setulose, with femur without long setae, tibia bearing an apicoventral spur. Wing. Most of the left wing lost, right wing intact, but twisted and rolled up on itself. The wing features are not described here in order to avoid detaching the one remaining wing for proper study. Halter yellowish.

Abdomen. Dark brown, with very narrow whitish stripes on posterior margins of each tergite; setal vestiture as usual for the genus. Male terminalia. Epandrium large, bearing some very long, strong setae; anterior surstylus rodlike, distinctly swollen apically, protruding forward, bearing some thin setulae on ventral side; posterior surstylus short, stumpy, with several stout spinulae and very robust setulae on ventral side; cercus of normal shape; phallus ribbon-like, with dense, long setulae ventrally on basal half, several short setulae on distal half; ejaculatory apodeme and phallapodeme as usual for the subfamily.

Female. Unknown.

Type material. The holotype ♂ of Dasyrhicnoessa dolichopoda sp. nov. is labelled “[printed white label] Solomon Is: / Guadalcanal I. / Honiara. [9°26′S 159°57′E] / 9 – 10.x.1953 / J.D. Bradley. // [printed white label] Rennell I. / Expedition. / B.M. 1954-222. // [printed red label] Holotypus / Dasyrhicnoessa / dolichopoda sp. nov. ♂ / L. Munari des. 2013”. The holotype is double mounted (glued to a celluloid triangle), is in fairly good condition (left wing and tarsus of left hind leg lost, mesonotum slightly collapsed medially, right wing twisted and rolled up on itself), with the abdomen removed, dissected, and stored in a small plastic tube filled with glycerol and pinned below the specimen. The holotype is deposited in the Natural History Museum, London, UK.

Distribution. Solomon Islands (Guadalcanal).

Etymology. The species epithet, dolichopoda , is a compound name of ancient Greek derivation and refers to the legs being relatively slender and slightly longer than in most of its congeners.

Remarks. Dasyrhicnoessa dolichopoda sp. nov. shows a characteristic habitus that is typified mainly by the unusually large and porrect antenna, with an entirely black basal flagellomere; by having only four peristomal setae, including true vibrissa; by the acrostichal setulae that are arranged in four irregular rows; and especially by the slender legs that are perceptibly longer than usual, with an entirely black foretibia and foretarsus. The morphology of the external male terminalia very roughly resembles that of the Pacific species D. aquila Munari, 2002 , and D. atripes Munari, 2004 , both characterized by a fairly large, protrudent anterior surstylus, which is always very characteristically shaped in each of these species, and a stocky posterior surstylus. However, these “similarities” are purely superficial and are confined to the lateral view only, posterior view exhibiting substantially different morphologies. Additionally, the combination of the above-mentioned external characters is quite different between the three species.

Figures

FIGURES 1 – 2. ♂ terminalia of Dasyrhicnoessa dolichopoda sp. nov.. 1: lateral view; 2: posterior view. Scale bar = 0.1 mm.